Comparative Evaluation of Single and Hybrid Reinforcements in Aluminum Matrix Composites: Effects of SiC, Si3N4 and TiO2 Content on Mechanical and Tribological Properties

Aluminum matrix composites (AMCs) are attractive lightweight materials whose properties can be modified by the type and amount of ceramic reinforcement. In this study, Al–SiC composites containing 2 or 5 wt.% SiC were compared with hybrid Al–SiC–Si3N4 and Al–SiC–TiO2 composites containing 2 + 2 or 5 + 5 wt.% reinforcement. The materials were produced by powder mixing, pre-compaction and hot extrusion. Their microstructure, phase composition, relative density, hardness, mechanical properties and wear behavior were investigated. All materials had high relative densities of 97.48–99.99%. The TiO2-containing composites showed the highest compressive stresses, approximately 202–204 MPa at 20% strain and 277–279 MPa at 40% strain, but much lower flexural stresses than the other materials. The highest flexural stress (420 MPa) was obtained for 2SiC + 2Si3N4. The highest hardness (49 HB) was measured for 5SiC + 5TiO2, which also had the lowest mass loss after 500 m (0.335%), although its mean coefficient of friction was the highest. These results show that the most favorable reinforcement composition depends on the property considered. These findings highlight the importance of selecting reinforcement types and contents according to the intended application, supporting resource-efficient design of aluminum matrix composites and providing a basis for further evaluation of their sustainability.